Here's my problem concerning a class diagram. Let there be two classes : a class Graph and a class View. A view is an aggregation of 1..* graphs and a graph is contained in 1..* views. This can be modelled very simply. I also would like to model that there exists 0..1 'target' view for a given couple (graph, 'source' view). To be clearer, given a graph and a view that contains it, one can reach (by clicking on the graph for instance) zero or one view (said the target view). How can I model this ? I've thought of a ternary association between Graph, View (with the role target) and View (with the role source). This seems strange to me… Looking forward to hearing   More>>